Recently completed some restorations and modifiactions,
Here is a list of events/summary of issues after completing some restoration (removed and reinstalled tub to fix rust issues, replaced rear axle, installed 1" body lift, installed 4" rough country suspension lift, replaced fuel tank):
1) Wouldn't start fuel pump not running, jumped fuel pump to verify it worked, but still wouldn't start
2) Checked ECU, 1st imprinted circuit from Pin3 to 1st Diode/resistor/?? fried
3) Installed Jumper #1 on circuit board by soldering a piece of phone wire
4) fuel pump runs when key is turned on, jeep runs
5) Drove about 5-10 minutes, jeep died, fuel pump not running when key is turned on
5) Checked ECU, jumper #1 is fried
6) Found insulation missing on injector connector wires, replaced injector connector
7) Installed jumper #2 to replace jumper #1
8) Fuel pump runs when key is turned on, jeeps runs, passed inspection
9) drove 2-3 hours total over 1-2 week period
10) jeep dies pulling out of drive way, fuel pump not running when key is turned on
11) checked ECU, jumper #2 is fried
12) Installed jumper #3 using CAT 5 wire to replace jumper #2
13) Drove a couple of hours over a 1 week period
14) After driving to a location and parking for about 1 hour, jeep will not start, fuel pump not running
15) checked ECU, jumper #3 looks good
16) checked for additional bad wires, found 4 wires that connect to side of transmission that appear to come into contact with exhaust and have insulation missing, taped wires to prevent short
17) fuel pump runs when key is turned on, jeep runs
18) After driving to a location and parking for about 7 hours, jeep will not start, fuel pump not running
19) After sitting for 2 days in garage, fuel pump runs when key is turned on, jeep runs
20) On Friday drove to store came home (2 times), went to go to a 3rd location, jeep will not start, fuel pump not running
21) checked ECU, jumper #3 looks good
I've looked for bad wires and loose grounds, but I'm not sure what else to do at this point. I'm not sure if the ECU needs to be repaired/replaced, but I don't want to do that if there is another issue that is causing the ECU to fail.
pls tell us some basic info about your jeep...what engine, trans, carb'd or injected?
just reading if your rig is standard your have the injected 4cyl?
so....when your fuel pump "won't run" have you checked to see if it's getting voltage? could be something as simple as a bad fuel pump.
a l'il info and you'll get some responses.
just my .02
edit: guess i was too lazy to check, but just checked your profile. you do have the 2.5L so i know it's injected. what trans ? is there a cps? if so, has it or its wiring been verified as good?
When the fuel pump is not running you need to measure the voltage at the connector in the rear to see if you are getting voltage to the plug. The ground is bad so you need to measure the voltage 2 times, 1 with power refrenced to the connector ground the the other to the chasis. To do this you need to have someone to cycle the key while you do the measurement or jumper the fuel pump relay socket between pins 30 and 87 under the hood on the passenger side of the engine compartment. Do you have a manual and meter to work with? You will be needing both. There is a recent post to download the factory manual. You can find it easy if you search. I strongly recomment you download the fsm if you dont have it.